﻿using System;

namespace RpcHelper
{

        public class GpsUtil
        {
                public static double pi = 3.1415926535897932384626;
                public static double x_pi = 3.14159265358979324 * 3000.0 / 180.0;
                public static double a = 6378245.0;
                public static double ee = 0.00669342162296594323;

                public static double TransformLat(double x, double y)
                {
                        double ret = -100.0 + (2.0 * x) + (3.0 * y) + (0.2 * y * y) + (0.1 * x * y) + (0.2 * Math.Sqrt(Math.Abs(x)));
                        ret += ((20.0 * Math.Sin(6.0 * x * pi)) + (20.0 * Math.Sin(2.0 * x * pi))) * 2.0 / 3.0;
                        ret += ((20.0 * Math.Sin(y * pi)) + (40.0 * Math.Sin(y / 3.0 * pi))) * 2.0 / 3.0;
                        ret += ((160.0 * Math.Sin(y / 12.0 * pi)) + (320 * Math.Sin(y * pi / 30.0))) * 2.0 / 3.0;
                        return ret;
                }

                public static double TransformLon(double x, double y)
                {
                        double ret = 300.0 + x + (2.0 * y) + (0.1 * x * x) + (0.1 * x * y) + (0.1 * Math.Sqrt(Math.Abs(x)));
                        ret += ((20.0 * Math.Sin(6.0 * x * pi)) + (20.0 * Math.Sin(2.0 * x * pi))) * 2.0 / 3.0;
                        ret += ((20.0 * Math.Sin(x * pi)) + (40.0 * Math.Sin(x / 3.0 * pi))) * 2.0 / 3.0;
                        ret += ((150.0 * Math.Sin(x / 12.0 * pi)) + (300.0 * Math.Sin(x / 30.0
                                * pi))) * 2.0 / 3.0;
                        return ret;
                }

                public static double[] transform(double lat, double lon)
                {
                        if (OutOfChina(lat, lon))
                        {
                                return new double[] { lat, lon };
                        }
                        double dLat = TransformLat(lon - 105.0, lat - 35.0);
                        double dLon = TransformLon(lon - 105.0, lat - 35.0);
                        double radLat = lat / 180.0 * pi;
                        double magic = Math.Sin(radLat);
                        magic = 1 - (ee * magic * magic);
                        double SqrtMagic = Math.Sqrt(magic);
                        dLat = dLat * 180.0 / (a * (1 - ee) / (magic * SqrtMagic) * pi);
                        dLon = dLon * 180.0 / (a / SqrtMagic * Math.Cos(radLat) * pi);
                        double mgLat = lat + dLat;
                        double mgLon = lon + dLon;
                        return new double[] { mgLat, mgLon };
                }

                public static bool OutOfChina(double lat, double lon)
                {
                        return lon < 72.004 || lon > 137.8347 || lat < 0.8293 || lat > 55.8271;
                }

                /** 
                    * 84 to 火星坐标系 (GCJ-02) World Geodetic System ==> Mars Geodetic System 
                    * 
                    * @param lat 
                    * @param lon 
                    * @return 
                    */
                public static double[] Gps84ToGcj02(double lat, double lon)
                {
                        if (OutOfChina(lat, lon))
                        {
                                return new double[] { lat, lon };
                        }
                        double dLat = TransformLat(lon - 105.0, lat - 35.0);
                        double dLon = TransformLon(lon - 105.0, lat - 35.0);
                        double radLat = lat / 180.0 * pi;
                        double magic = Math.Sin(radLat);
                        magic = 1 - (ee * magic * magic);
                        double SqrtMagic = Math.Sqrt(magic);
                        dLat = dLat * 180.0 / (a * (1 - ee) / (magic * SqrtMagic) * pi);
                        dLon = dLon * 180.0 / (a / SqrtMagic * Math.Cos(radLat) * pi);
                        double mgLat = lat + dLat;
                        double mgLon = lon + dLon;
                        return new double[] { mgLat, mgLon };
                }

                /** 
                    * * 火星坐标系 (GCJ-02) to 84 * * @param lon * @param lat * @return 
                    * */
                public static double[] Gcj02ToGps84(double lat, double lon)
                {
                        double[] gps = transform(lat, lon);
                        double lontitude = (lon * 2) - gps[1];
                        double latitude = (lat * 2) - gps[0];
                        return new double[] { latitude, lontitude };
                }
                /// <summary>
                /// 火星坐标系 (GCJ-02) 与百度坐标系 (BD-09) 的转换算法 将 GCJ-02 坐标转换成 BD-09 坐标 
                /// 高德谷歌转为百度
                /// </summary>
                /// <param name="lat"></param>
                /// <param name="lon"></param>
                /// <returns></returns>
                public static double[] Gcj02ToBd09(double lat, double lon)
                {
                        double x = lon, y = lat;
                        double z = Math.Sqrt((x * x) + (y * y)) + (0.00002 * Math.Sin(y * x_pi));
                        double theta = Math.Atan2(y, x) + (0.000003 * Math.Cos(x * x_pi));
                        double tempLon = (z * Math.Cos(theta)) + 0.0065;
                        double tempLat = (z * Math.Sin(theta)) + 0.006;
                        double[] gps = { tempLat, tempLon };
                        return gps;
                }

                /// <summary>
                /// 火星坐标系 (GCJ-02) 与百度坐标系 (BD-09) 的转换算法 * * 将 BD-09 坐标转换成GCJ-02 坐标
                /// 百度坐标转为高德谷歌坐标
                /// </summary>
                /// <param name="lat"></param>
                /// <param name="lon"></param>
                /// <returns></returns>
                public static double[] Bd09ToGcj02(double lat, double lon)
                {
                        double x = lon - 0.0065, y = lat - 0.006;
                        double z = Math.Sqrt((x * x) + (y * y)) - (0.00002 * Math.Sin(y * x_pi));
                        double theta = Math.Atan2(y, x) - (0.000003 * Math.Cos(x * x_pi));
                        double tempLon = z * Math.Cos(theta);
                        double tempLat = z * Math.Sin(theta);
                        double[] gps = { tempLat, tempLon };
                        return gps;
                }

                /// <summary>
                /// gps84转为bd09
                /// GPS坐标转为百度坐标
                /// </summary>
                /// <param name="lat"></param>
                /// <param name="lon"></param>
                /// <returns></returns>
                public static double[] Gps84ToBd09(double lat, double lon)
                {
                        double[] gcj02 = Gps84ToGcj02(lat, lon);
                        double[] bd09 = Gcj02ToBd09(gcj02[0], gcj02[1]);
                        return bd09;
                }
                /// <summary>
                /// 百度坐标转成GPS坐标
                /// </summary>
                /// <param name="lat"></param>
                /// <param name="lon"></param>
                /// <returns></returns>
                public static double[] Bd09ToGps84(double lat, double lon)
                {
                        double[] gcj02 = Bd09ToGcj02(lat, lon);
                        double[] gps84 = Gcj02ToGps84(gcj02[0], gcj02[1]);
                        //保留小数点后六位  
                        gps84[0] = Retain6(gps84[0]);
                        gps84[1] = Retain6(gps84[1]);
                        return gps84;
                }

                /// <summary>
                /// 保留小数点后六位 
                /// </summary>
                /// <param name="num"></param>
                /// <returns></returns>
                private static double Retain6(double num)
                {
                        return Math.Round(num, 6);
                }
        }
}
